New Kawasaki Stern Bulb System Provided Impressive Fuel Savings On Trial Run
The first ship equipped with a newly developed propulsive power saving system — the Kawasaki Stern End Bulb (Kawasaki-SEB) —was placed in service recently, showing excellent results. The installation was made on the 3,700- gt, 11,600-bhp Sutoretai Maru, a passenger vessel owned by Tokai Risen Company, Ltd. and the Maritime Credit Corporation. She serves on the Tokyo-Miyake Island- Hachijo Island route.
The Kawasaki-SEB was fixed on the ship's main stern hull around the center line and near the full-load waterline. The aim is to save propulsive power by reducing wave pattern resistance and stern part local resistance by the effect of the interference between the waves generated by the bulb and by the stern hull.
The basic theory of the SEB was developed by a research group led by Prof. Dr. T. Inui of Tokyo University, a world-famous authority on wave-making resistance theory. Under the guidance of this group, KHI has continued to study the SEB for practical use, and succeeded in its development. The SEB was installed on the Sutoretia Maru at a shipyard in Shimoda, a port situated on the Izu Peninsula.
In a speed trial conducted after the installation of the SEB, the ship recorded approximately 5 percent saving of propulsive power at the service speed of 20.8 knots, compared with performance when she was built. Furthermore, the ship gained about 0.25 knots more speed at the same cruising power.
When the system is installed on a large car ferry or containership, Kawasaki estimates it will produce an annual saving in fuel costs of about 70 million yen ($335,000).